Method, apparatus, and medium for bandwidth extension encoding and decoding

Abstract

Provided are a method, apparatus, and medium for encoding/decoding a high frequency band signal by using a low frequency band signal corresponding to an audio signal or a speech signal. Accordingly, since the high frequency band signal is encoded and decoded by using the low frequency band signal, encoding and decoding can be carried out with a small data size while avoiding deterioration of sound quality.

What is claimed is: 
     
       1. A method of bandwidth extension decoding, comprising:
 checking whether a signal is encoded in a first domain or a second domain other than the first domain; 
 lossless decoding and de-quantizing the signal, and inverse-transforming the de-quantized signal to the second domain if the checking result shows that the signal is encoded in the first domain; 
 decoding the signal using CELP (code excited linear prediction) if the checking result shows that the signal is encoded in the second domain; 
 transforming the signal that is inverse-transformed to the second domain, by using a quadrature mirror filterbank (QMF), or transforming the signal that is decoded using the CELP, by using the QMF; 
 generating, in a QMF domain, a high band signal using the transformed signal; 
 generating a stereo signal from the high band signal and the transformed signal; and 
 inverse-transforming the stereo signal, by using an inverse QMF, 
 wherein the method is performed using at least one processor. 
 
     
     
       2. An apparatus for bandwidth extension decoding, comprising:
 a domain checking unit which checks whether a signal is encoded in a first domain or a second domain other than the first domain; 
 a first decoding unit which performs lossless decoding and de-quantization of the signal, and which inverse-transforms the de-quantized signal to the second domain if the checking result shows that the signal is encoded in the first domain; 
 a second decoding unit, implemented using a processor, which performs decoding the signal using CELP (code excited linear prediction) if the checking result shows that the signal is encoded in the second domain; 
 a transform unit which transforms the signal that is inverse-transformed to the second domain by using a quadrature mirror filterbank (QMF), or transforms the signal that is decoded using the CELP, by using the QMF; 
 a high band generating unit which generates, in a QMF domain, a high band signal using the transformed signal; 
 a stereo signal generating unit which generates a stereo signal from the high band signal and the transformed signal; and 
 an inverse transform unit which inverse-transforms the stereo signal, by using an inverse QMF. 
 
     
     
       3. The method of  claim 1 , wherein the signal corresponds to a band signal lower than a predetermined frequency. 
     
     
       4. The apparatus of  claim 2 , wherein the signal corresponds to a band signal lower than a predetermined frequency. 
     
     
       5. The method of  claim 1 , wherein the first domain is a frequency domain. 
     
     
       6. The method of  claim 1 , wherein the second domain is a time domain. 
     
     
       7. The apparatus of  claim 2 , wherein the first domain is a frequency domain. 
     
     
       8. The apparatus of  claim 2 , wherein the second domain is a time domain.